In typical railroad systems, sections of track are connected electrically into circuits for control, monitoring, heating and/or maintenance purposes. Each track section forms a track circuit in which the track rails are utilized to carry an electrical signal. In some cases, the track rails in each section are electrically insulated from the track rails of adjacent track sections such that each circuit may be utilized individually for control and monitoring.
Monitoring the track circuit provides a means for detecting the presence or absence of a train, railroad vehicle, equipment and/or any foreign apparatus that activates or otherwise interacts with a given track section. For instance, it is customary to detect the presence of a railroad vehicle in a particular track section by detecting the presence of a short circuit or other variation in a signal being monitored through the rails of the parallel tracks.
In addition to the monitoring circuitry, it is common in northern climates for the railway tracks to have a heating system to melt snow and ice, particularly for the movable point blades at rail switches. Various track heating systems are known, including gas or electric forced air systems which blow hot air through a rail tie duct to melt snow and ice from the railway tracks. The tie duct is installed orthogonally beneath the rails, like any other rail tie, to support and connect the pair of parallel rails.
In a forced air system used to remove snow from point rails on railway tracks, the tie duct must be electrically isolated from each track, so as to prevent a short circuit from occurring and causing a potential false alarm for signalling and monitoring purposes.
Prior-art technologies used in the rail industry involve gaskets made from rubber and other electrically insulating materials. Not only do these gaskets complicate assembly and disassembly for maintenance but they are also prone to failure over time due to vibration and weathering.
An improved technology for electrically isolating the duct from the track would be highly desirable.